Impact of diet on pain perception in women with endometriosis: A systematic review

Introduction: Endometriosis is a painful, chronic inflammatory disorder that is difficult to treat. Studies have suggested that diet may have a therapeutic effect on chronic inflammation. However, only limited information is available regarding the impact of diet on pain perception in relation to endometriosis. As such, the aim of this review was to evaluate if diet has any impact on pain perception in women suffering from endometriosis. Materials and methods: A systematic review was conducted by searching Medline and Embase to identify randomized controlled trials and observational studies adhering to the PRISMA and SWiM guidelines. A table summarizing the findings was developed using the GRADE approach. Inclusion criteria were: women of reproductive age; laparoscopically confirmed diagnosis of endometriosis; and intervention including any type of dietary change. This review was registered with PROSPERO on 14 November 2020 (CRD42020212314). Results: In total, the database search identified 2185 studies; of these, six studies fulfilled the inclusion criteria. The Newcastle–Ottawa scale and the Cochrane tool were used to assess the studies, which were concluded to be of high quality and to have low risk of bias. All studies had a positive impact on pain perception, with all except one study reporting a significant reduction in pain perception, indicating that high intake of polyunsaturated fatty acids, a gluten-free diet and a low nickel diet may improve painful endometriosis. It was not possible to conduct a meta-analysis due to considerable heterogeneity amongst the included studies due to differences in dietary adherence, dietary therapies, outcome measurements, populations, durations and study designs. Conclusion: All studies found that diet had a positive impact on pain perception among women with endometriosis. However, the majority of available evidence on dietary interventions in relation to endometriosis-associated pain was derived from non-randomized controlled trials, which have multiple sources of bias. Therefore, further studies are needed to investigate diet and its effect on pain perception in women with endometriosis.